Safety bolt

ABSTRACT

A safety bolt having a headed end, a shank, and a threaded end, with means near the threaded end to hold the bolt in a hole even though the nut may have fallen off the thread or not have been put on it in the first place. An axial passage in the threaded end intersects a laterally extending passage spaced therefrom, and a dog fills the laterally extending passage and is laterally reciprocable so as to be entirely retracted or extended beyond the maximum diameter of the shank. The dog is biased to its extended position, and carries a retraction surface to retract it as the bolt is thrust into a hole and a restraint surface to retain the bolt after the dog has passed through the hole in a workpiece. Ratchet means may be formed on the dog and on a nut threadable to the bolt so as to retain the nut on the bolt.

t [72] Inventor United States Patent Robert R. Reddy 1195 Michillinda,Pasadena, Calif. 91107 [2|] Appl. No. 834,231

[22] Filed June 11, 1969 [45] Patented Feb. 9, 1971 Continuation ofapplication Ser. No. 619,233, Feb. 28, 1967, now abandoned.

[54] SAFETY BOLT 9 Claims, 26 Drawing Figs.

[52] U.S.Cl 151/9, 24/211; 151/69 [5 l] Int. Cl .Q. ..F16b 39/32, Fl6b43/00 [50] FieldolSearch............. ....151/9,

1,597,667 8/1926 Blair 151/9 Primary Examiner-Ramon S. BrittsAttorney-Angus & Mon

ABSTRACT: A safety bolt having a headed end, a shank, and

a threaded end, with means near the threaded end to hold the bolt in ahole even though the nut may have fallen off the thread or not have beenput on it in the first place. An axial passage in the threaded endintersects a laterally extending passage spaced therefrom, and a dogfills the laterally extending passage and is laterally reciprocable soas to be entirely retracted or extended beyond the maximum diameter ofthe shank. The dog is biased to its extended position, and carries aretraction surface to retract it as the Ibolt is thrust into a hole anda restraint surface to retain thebolt after the dog has passed throughthe hole in a workpiece. Ratchet means may be formed on the dog and on anut threadable to the bolt so as to retain the nut on the bolt.

PATENTEU FEB 9mm 3.561516 SHEET 2 OF 2 SAFETY BOLT CROSS-REFERENCE TORELATED APPLICATIONS This application is a continuation of applicant'scopending U.S. Pat. pending application Ser. No. 6l9,233, filed Feb. 28,1967, now abandoned.

This invention relates to safety bolts. Especially in aircraft and otherheavy-type installations, the principal utility of a bolt is towithstand shear loads exerted laterally relative to its axis. Inpractice, a nut is supposed to be threaded onto the bolt in order tohold it in place, and to tighten the joint so as to be resistant tofatigue forces and to axial loads. However, the axial loads areordinarily of a considerably lesser magnitude than the shear loads andare not the primary intended function of the bolt.

When a nut shakes loose, or the mechanic neglects to put on the nut atall, a situation of very great danger arises, because the bolt couldsimply fall out of its hole, leaving disabled some critical element ofthe installation such as a landing gear or some other pivotally mounteddevice. To overcome this risk, there have been devised a class of boltknown as the "safety bolt" which includes within itself inherent meansfor axial retention which, while not as strong as a nut threaded ontothe bolt, still will hold the bolt in its hole under many, if not most,critical situations, and enable the bolt to perform its primary intendedfunction. If the nut is forgotten or shaken off, the bolt will remain inplace under many or most important conditions.

An obvious requirement of such a safety bolt is that it require no careor attention from the mechanic, because it is his failure or inattentionwhich causes the safety bolt to be needed in the first place. Instead,its action must be automatic, and the bolt itself should not beremovable except by the conscious and deliberate manipulation ofamechanic.

It is an object of this invention to provide an improved safety boltwith reliable bolt retention features which are at once strong andreliable, and which require conscious acts of manipulation before thebolt can be removed, and which may, if desired, be automaticallyretractable when the bolt is installed. There is provided a completelyreliable safety bolt which overcomes the most dangerous, if not all, ofthe risks inherent in a mechanic's carelessness.

An optional objective of this invention is to provide a ratcheting meanswhich will retain a nut and prevent it from loosening. I

A safety bolt according to this invention includes a shank with a firstheaded end and a second threaded end. An axial passage is formed in theshank from the second end, and extends through and just beyond thethreaded section at which point there is at least one intersectinglateral passage in which a laterally reciprocable dog is disposed. Thisdog has a restraint surface which is adapted to be retracted within thecylindrical surface of the bolt by motion of a cam member that must bemanipulated by the mechanic in order to retract the dog. It may beextended beyond the cylindrical surface by springing or other biasmeans.

According to a preferred but optional feature of the invention, the cammember and the locking dog include, mutually interacting cam surfaceswhich by axial movement of the cam in one embodiment, or rotary movementof the cam in another embodiment, causes retraction of the locking dog.

According to a preferred embodiment of the invention, a plurality ofthese dogs is provided which are opposed to each other, and interposedbetween them is a spring for bias purposes.

According to still another preferred but optional feature of thisinvention, the locking dog may be provided with ratchet faces, and a nutto be threaded onto the threads of the bolts also is provided withratchet faces. The nut is retained in a tightened position by virtue ofthe interaction between the sets of ratchet faces.

The above and other features of this invention will be fully understoodfrom the following detailed description and the accompanying drawings inwhich:

FIG. I is a side elevation partially in cross section showing thepresently preferred embodiment of the invention;

FIG. 2 is a partial right-hand view taken at line 2-2 of FIG. 1;

FIG. 3 is a side elevation partly in axial cross section showing aportion of the device of FIG. 1;

FIG. 4 is a right-hand end view taken at line 4-4 of FIG. 3;

FIG. 5 is a side elevation of another portion of the device of FIG. 1;

FIGS. 6 and 7 are a right-hand side view and a top view, respectively,taken at lines 6-6 and 7-7 of FIG. 1;

FIG. 8 is a side elevation of another portion of FIG. 1;

FIG. 9 is a right-hand side view taken at line 9-9 of FIG. 8',

FIG. 10 is a fragmentary axial view partly in cutaway cross sectionshowing a portion of the device of FIG. 1 in the operating condition ofFIG. 1;

FIG. 11 is a view similar to FIG. Ill) showing the device in anotheroperating configuration;

FIG. 12 is a fragmentary axial cross section of a modification of thedevice of FIG. 1;

FIG. 13 is a side elevation of an alternate embodiment of the portion ofthe invention shown in FIGS. 57;

FIG. 14 is a top view taken at line 14-14 of FIG. 13;

FIG. 15 is a side elevation of an alternate embodiment of that portionof FIG. I shown in FIGS. 8 and 9;

FIG. 16 is a side view taken at line 16-16 of FIG. 15;

FIG. 17 and 18 are fragmentary top views showing the interaction betweenthe elements of FIGS. 13-16 in two operating positions;

FIG. 19 shows the devices of FIGS. 13-16 in use in the bolt of FIG. 1;

FIG. 20 is an end view of a nut suitable for use with any embodiment ofthe invention;

FIG. 21 is an end view of a modified locking dog for use with the nut ofFIG. 20;

FIG. 22 is a bottom view taken at line 22-22 of FIG. 21;

FIG. 23 is a fragmentary view partly in cutaway cross section showingthe interrelationship of the devices of FIGS. 20 and 21;

FIG. 24 is a side elevation of yet another alternate embodiment of thatportion of FIG. 1 shown in FIGS. 8 and 9; and

FIGS. 25 and 26 are fragmentary side and top views taken at lines 25-25and 26-26, respectively, of FIG. 24.

FIG. 1 illustrates the presently preferred embodiment of the safety boltassembly 30 according to the invention. It is shown clamping threeplates 31, 32, 33 together. However, the bolt is primarily intended towithstand shear forces which are exerted laterally relative to axis 34of the safety bolt. The safety bolt includes a head 35 at a first end36, a threaded section 37 adjacent to a second end 38, and a cylindricalshank 39 having a cylindrical outer wall extending between the head andthe thread.

A pair of locking dogs 40, 41 are shown projecting beyond the wall ofthe cylindrical shank. They bear against plate 33 while the head bearsagainst plate 31. It is the function of these locking dogs to hold thesafety bolt in place against some axial loads.

A nut 42 with a countersink 43 is adapted to be threaded onto thethreaded section to perform the major function of axial restraint. Thisnut is shown in dashed line to indicate that it is one purpose of thisinvention to make the bolt safe against the mechanic's forgetfulness inapplying the nut or of applying it so loosely that it may fall off dueto vibratory forces and the like. The application with a nut is shown inFIGS. 20-23. In the application of FIG. 1, which does not illustrate aratcheting feature, the counterbore clears the dogs.

As best shown in FIG. 3, the bolt portion 45 includes an axial passage46 which opens onto first end 38. A pair of lateral passages 47, 48intersect the axial passage and open onto the wall of the cylindricalshank, spaced from the threaded section. There may be only one of theselateral passages, or there may be two or more. Ordinarily, it ispreferred to have two of he lateral passages opposed and aligned, sothat two locking dogs may be used with a simple bias means interposedbetween them. A guide base 49 is formed at the bottom of the axialpassage to form a continuation of the lateral passages so as to givebottom support to the locking dogs as they reciprocate in theirrespective passages.

A cam member 50 (FIGS. -7) comprising a cylindrical sidewall 50a adaptedto fit slideably in the axial passage includes a flat end 51, and an endmodified for camming purposes on the other extreme. This other end isreadily formed by milling in one direction (FIG. 5) a V-shaped slot 52to form a pair of cam surfaces 53, 54. At 90 thereto (FIG. 6), there ismilled a flat slot 55 which is adapted to straddle a portion of alocking dog, and whose wall 56 constitutes a guide means.

A locking dog is provided in each lateral passage. The locking dogs areidentical, and only dog 40 is shown in FIGS. 8 and 9. The dogs have agenerally cylindrical sidewall 57 and, as shown in FIG. 7, also includea sloped cam surface 58 with substantially the same pitch as camsurfaces 53 and 54. A bar portion 59 is adapted to fit in slot 55 withwalls 56 abutting it. A projection 60 includes a restraint surface 61which is flat and parallel to the axis 62 of the locking dog, and also aretraction surface 63 which is sloped relative to the axis, facilitatingthe retraction of the dogs into the bolt portion when it is being passedthrough the hole in the plates. A snap ring 6311 retains the cam memberin the axial passage, and limits its retraction so that the cam memberholds the dogs in their respective lateral passages.

It will now be seen that, with the locking dogs in their lt spectivelateral passages, they may be pulled inwardly by force of the camsurfaces 53, 54 exerted against cam surfaces 58. Motion in the otherdirection (which includes expulsion movement, to the right in FIG. 1, ofthe cam member) is performed by bias means 65 shown in FIG. as a coil orleaf spring interposed between the two locking dogs and seated in sinks66 in the base of the locking dogs.

The assembled configuration is shown in FIGS. 10 and 11 in two operativeconditions. In FIG. 10, the cam member 50 is moved to the right, and thelocking dogs have been moved outwardly by action of the bias means. InFIG. 11, the cam member has been pressed to the left as indicated byarrow 67 and this has caused the cam surfaces to interact and to retractthe locking dogs within the cylindrical wall of the shank.

FIG. 1.2 illustrates an optional feature comprising a spring 70 incompression between a shoulder 71 fixed to member 45 inside its axialpassage and a flange 72 on a cam member 73. The coil spring 65, bypressing the dogs against the cam member, tends to bias the cam memberto the right, thereby assuring that the bias means will be able toextend the locking dogs without interference from the cam member in allembodiments. Spring 70 adds to this effect by biasing the cam memberitself away from the dogs. In all embodiments, the cam member alwaysoverhangs a portion of each of the dogs, to keep the dogs from fallingout.

The device heretofore described utilizes axial movement of the cammember to retract the locking dogs. It should be understood that this isonly one type of motion which would be effective for the purpose. InFIGS. 13-19, the use of a rotary camming motion is shown. The same boltportion 45 will be used as in FIG. 1, only the cam member and lockingdogs being modified. In FIGS. 13 and 14, there is shown a cam member 75having an axis 76 about which the cam member is intended to be rotated.In one end, it has a cross slot 77 which is engageable by a screw driveror other torque-type tool for turning the same.

In its other end, it includes a cam recess 78 which includes a camsurface 79, which cam surface includes a pair of stops 80, 81. The camsurface projects for a different distance from the central axis as afunction of angular position in accordance with usual cam techniques.

In FIGS. and 16, there is shown an example of a locking dog 85 suitablefor use with can member 75. This cam member has an axis 86 along whichit is intended to be reciprocable in its respective lateral passage. Itincludes a restraint surface 37 and a retraction surface 88 as in FIGS.8

and 9. It differs from the device of FIGS. 8 and 9 in that its camsurface 89 is formed on a lug portion 90 adapted to overhang the cammingend of the cam member and engage the cam surface thereof.

FIGS. 17 and 18 show two relative positions of cam member 75 and lockingdog 85. In FIG. 16, the cam member is turned so that the locking dog hasmoved by its greatest axial excursion to the right. This is the lockingcondition. In FIG. 18, the cam member hasfibeenturned so as to retractthe locking dog by moving it to the left. This is the unlockedcondition.

FIG. I9 shows the total device in great detail.

When the nut is turned onto the threads of the safety bolt, there isstill the risk that it may shake loose. For this purpose, it is commonpractice to provide cotter pins, safety wires, and the like. Thisinvention is further adapted to provide additional safety means, whichcan do without conventional safety means, and be automatic in itsaction.

One embodiment is shown in FIGS. 20-23, wherein a nut of standardconfiguration including a central threaded passage 96 is modified by theinclusion of ratchet faces 97. Either of the embodiments of the lockingdogs may be modified as shown in FIGS. 21 and 22 to include a ratchetface 98. Because of the spring bias against the locking dogs, they canbe pressed back into the lateral passages as the ratchet faces move pastthe dogs or the nut is being tightened down. They will then snap intothe recesses 97a and the ratchet faces will abut to prevent loosening ofthe nut when tightening is complete. The joint is then locked until thedogs are retracted by actuation of the cam member.

Still another ratcheting, nut retaining dog is shown in FIGS. 24-26.This dog has a square cross section, which indicates that the lateralpassage need not be round, but may be of any shape. In a ratchet device,the noncircular cross section has the advantage of preventing rotationof the dog.

Dog 100 fits into a square lateral passage 101 in a bolt 45 modified inthis manner. It includes cam surfaces 102 which are identical tosurfaces 58, and are adapted to be acted upon by cam member 50 just asdog 40 is acted upon by that cam member. A restraint surface 103 facestoward the headed end. Face 104 is a ratcheting face to engage a likeface in the counterbore of a nut such as nut 95. A canted face 105 isflat, and slopes away from the axis as it extends toward the headed end,and also as it extends toward the ratcheting face. This combination ofslopes enables the dog to be pressed into the lateral passage as itpasses through a hole in the plate in which it is to be installed, andalso when the nut ratchets across the dog. This retraction is madepossible by the spring bias.

Additional, and more conventional, safetying features may also be usedwith any embodiment. For example, in FIG. 19, there is shown a lockwirehole 1 10 drilled through the wall of the threaded portion, with alockwire Ill passing through it, and through the slot in the retainingcam. Now the cam cannot be turned to release the bolt without firstremoving the safety wire. This is merely one example of the many kindsof additional securement which can be provided by preventing themovement of the cam member.

In this invention, a flat retention surface is preferably used, becausethis avoids brinnelling, which can occur when rounded surfaces, such asballs, are used. Furthermore, this results in placing the load on thedogs in the form of a pure shear load, and does not tend to place thedogs under compressive or other types of loads which have undesirableeffects. Retraction surfaces 88 are preferably nonperpendicular tocentral axis 34, because then there need be no act of retraction priorto insertion of the bolt-the dogs simply retracting by virtue of contactwith the wall of the hole on the way in. The device is then inherentlyreliable, there being no means provided which might be overlooked andkeep the dogs retracted.

This invention thereby provides a safety bolt in which a joint issecured against forgetfulness of the mechanic by the simple act ofinstalling the bolt itself. The bolt may readily be removed by actuationof a cam member, but the actuation of this cam member requires positivemanipulation which cannot result from accidentally or randomly exertedforces. The device does not interfere with the strength of the boltwhere it must carry its major lateral loads nor does the hole throughthe threaded portion reduce the strength of that portion below itsdesign levels. The safetying device itself need not be overly large,and, in fact, may take up only a minor portion of the cross-sectionalarea of the bolt wherever it is installed. More or fewer dogs may beprovided, depending on the strength of the retention desired. It will befurther noted that the dogs are backed up by strong sections of the boltportion and that this abutment is in itself a very strong and reliableretention means against axial loads, and is completely proof againstvibrational loads, because it cannot shake out or off.

This device may include an additional safetying feature such as theratcheting lock.

This invention is not to be limited by the embodiments shown in thedrawings and described in the description which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

l. A safety bolt comprising: an element having a shank with an axis andan unthreaded portion, the element having a first headed end and asecond threaded end, an axial passage opening onto said second end, anda laterally extending passage opening onto the shank and intersectingthe axial passage; a dog slideably mounted between extended andretracted positions in said laterally extending passage whereby the dogextends beyond the maximum diameter of the shank in the extendedposition and retracts entirely within said shank in the retractedposition, said dog includinga planar restraint surface which lies normalto the said axis and faces the headed end, whereby it is adapted to abutthe back side of a body into which the shank is inserted, a retractionsurface facing toward the threaded end and sloping inwardly toward it,both of said surfaces being adapted to project beyond the radius of theunthreaded portion of the shank, whereby the restraint surface, whenextended, prevents the removal of the bolt by a force exerted in shear,and the retraction surface is adapted to engage the said body in orderfor the dog to be retracted into the bolt while the shank is beingpressed intoa hole in the body, the dog fully occupying the laterallyextending passage in cross section to create such shear relationship; acam member movable in said axial passage and reactive with said dog toretract the same; .and .bias means forcing the dog toward its extendedposition independently of the position of the cam member.

2. A safety bolt according to claim] in which said dog and- 3. A safetybolt according to claim 2 in which the cam member is axially movable,and in which the camming surfaces are slanted relative to said axis.

4. A safety bolt according to claim 2 in which the cam member isrotatable, and in which at least one of the cam surfaces has a pluralityof regions at different radial spacings from the axis.

5. A safety bolt according to claim 2 in which safetying means isprovided to secure the cam member against movement.

6. In combination: a safety bolt comprising an element having a shankwith an axis and an unthreaded portion, the ele ment having a firstheaded end and a second threaded end, an axial passage opening onto saidsecond end, a laterally extend ing passage opening onto the shank andintersecting the axial passage, a dog slideably mounted between extendedand retracted positions in said laterally extending passage whereby thedog extends beyond the maximum diameter of the shank in the extendedposition and retracts entirely within said shank in the retractedposition, said dog including a planar restraint surface which liesnormal to the said axis and faces the headed end, whereby it is adaptedto abut the back side of a body into which the shank is inserted, aretraction surface facin toward the threaded end and sloping inwardlytoward it, bot of said surfaces being adapted to project beyond theradius of the unthreaded portion of the shank, whereby the restraintsurface, when extended, prevents the removal of the bolt by a forceexerted in shear and the retraction surface is adapted to engage thesaid body in order for the dog to be retracted into the bolt while theshank is being pressed into a hole in the body, the dog fully occupyingthe laterally extending passage in cross section to create such shearrelationship, said dog including a ratchet face and a sloping retractionface, and a cam member movable in said axial passage and reactive withsaid dog to retract the same, bias means forcing the dog toward itsextended position, and a nut threadable onto the threaded end having aplurality of ratchet faces in a counterbore, whereby tightening the nutonto the threads causes the dog to ratchet along the ratchet faces ofthe nut, and the ratchet faces to engage and resist unthreading of thenut firom the bolt.

7. A combination according to claim 6 in which said dog and cam membereach has a camming; surface mutually reactive to retract the dog.

8. A combination according to claim 7 in which the cam member is axiallymovable, and in which the camming surfaces are slanted relative to saidaxis.

9. A combination according to claim 7 in which the cam member isrotatable, and in which at least one of the cam surfaces has a pluralityof regions at different radial spacings from the axis.

2' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent3,561,516 Dated February 9, 1971 Invent0r(s) Robert R. Reddy It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the Patent References Cited Patent No. "3,280,329" should be"3,208,329"

Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER, JR.

Commissioner of Patents Attesting Officer

1. A safety bolt comprising: an element having a shank with an axis andan unthreaded portion, the element having a first headed end and asecond threaded end, an axial passage opening onto said second end, anda laterally extending passage opening onto the shank and intersectingthe axial passage; a dog slideably mounted between extended andretracted positions in said laterally extending passage whereby the dogextends beyond the maximum diameter of the shank in the extendedposition and retracts entirely within said shank in the retractedposition, said dog including a planar restraint surface which liesnormal to the said axis and faces the headed end, whereby it is adaptedto abut the back side of a body into which the shank is inserted, aretraction surface facing toward the threaded end and sloping inwardlytoward it, both of said surfaces being adapted to project beyond theradius of the unthreaded portion of the shank, whereby the restraintsurface, when extended, prevents the removal of the bolt by a forceexerted in shear, and the retraction surface is adapted to engage thesaid body in order for the dog to be retracted into the bolt while theshank is being pressed into a hole in the body, the dog fully occupyingthe laterally extending passage in cross section to create such shearrelationship; a cam member movable in said axial passage and reactivewith said dog to retract the same; and bias means forcing the dog towardits extended position independently of the position of the cam member.2. A safety bolt according to claim 1 in which said dog and cam membereach has a camming surface mutually reactive to retract the dog.
 3. Asafety bolt according to claim 2 in which the cam member is axiallymovable, and in which the camming surfaces are slanted relative to saidaxis.
 4. A safety bolt according to claim 2 in which the cam member isrotatable, and in which at least one of the cam surfaces has a pluralityof regions at different radial spacings from the axis.
 5. A safety boltaccording to claim 2 in which safetying means is provided to secure thecam member against movement.
 6. In combination: a safety bolt comprisingan element having a shank with an axis and an unthreaded portion, theelement having a first headed end and a second threaded end, an axialpassage opening onto said second end, a laterally extending passageopening onto the shank and intersecting the axial passage, a dogslideably mounted between extended and retracted positions in saidlaterally extending passage whereby the dog extends beyond the maximumdiameter of the shank in the extended position and retracts entirelywithin said shank in the retracted position, said dog including a planarrestraint surface which lies normal to the said axis and faces theheaded end, whereby it is adapted to abut the back side of a body intowhich the shank is inserted, a retraction surface facing toward thethreaded end and sloping inwardly toward it, both of said surfaces beingadapted to project beyond the radius of the unthreaded portion of theshank, whereby the restraint surface, when extended, prevents theremoval of the bolt by a force exerted in shear and the retractionsurface is adapted to engage the said body in order for the dog to beretracted into the bolt while the shank is being pressed into a hole inthe body, the dog fully occupying the laterally extending passage incross section to create such shear relationship, said dog including aratchet face and a sloping retraction face, and a cam member movable insaid axial passage and reactive with said dog to retract the same, biasmeans forcing the dog toward its extended position, and a nut threadableonto the threaded end having a plurality of ratchet faces in acounterbore, whereby tightening the nut onto the threads causes the dogto ratchet along the ratchet faces of the nut, and the ratchet faces toengage and resist unthreading of the nut from the bolt.
 7. A combinationaccording to claim 6 in which said dog and cam member each has a cammingsurface mutually reactive to retract the dog.
 8. A combination accordingto claim 7 in which the cam member is axially movable, and in which thecamming surfaces are slanted relative to said axis.
 9. A combinationaccording to claim 7 in which the cam member is rotatable, and in whichat least one of the cam surfaces has a plurality of regions at differentradial spacings from the axis.